OnePlus has already provided users of its recent 7-series phones with OxygenOS based on Android 10 in the form of official Open Betas. However, those who have not opted into this program can also now upgrade to this new ROM on their devices. It contains numerous 10-specific updates and improvements.
https://www.notebookcheck.net/OnePlus-releases-its-first-stable-version-of-Android-10-for-the-7-and-7-Pro.438943.0.html